As a RICS Chartered Surveyor in France, I see that one of the largest causes of damage and degradation to houses is caused by the presence of damp. This in turn creates the perfect environment for wood rot and wood boring insects that can cause a huge amount of damage to timber structures. Damp in masonry may cause spalling and degradation of stonework and ‘blowing’ of render, in addition to corrosion of steel reinforcing rods within concrete structures. As the steel rusts it expands and the concrete surrounding the steel becomes detached. This compromises the structural capability and ultimately leads to failure.

RICS Surveyor in France. ‘Blown’ concrete around rusting reinforcing rods

All to often I see examples of damp being introduced to buildings as a result of modern building materials and repairs being inappropriately applied to houses of traditional construction.

However, there is an enormous and ever increasing promotion of so called ‘energy saving measures’ that seek to reduce energy consumption and CO2 emissions from houses. Despite the degradation caused by damp, ironically these initiatives often promote the eradication of drafts with the installation of modern windows that seal without any air gap, the introduction of draft seals and huge amounts of insulation to lofts.  Whilst such advice is well intentioned, sadly the logic is flawed and counter productive when applied to traditionally constructed properties. The reason is that older properties often have solid stone walls and floors, without damp proof course or cavity. The design on construction was to allow the damp to escape from the house via gaps in windows and beneath doors and through vapour permeable materials. This allows the house to ‘breathe’ and remain dry. This in turn allows the house to remain free from wood rot and insect attack etc.  

Modern window restricting ventilation

Even ignoring damp ingress through leaks etc, the production of water vapour can be huge from every day living including breathing, showers, cooking etc. From these every day activities, 4 occupants within a house will typically produce approximately 5 litres of water per day. So 150 litres of water carried within a much larger volume of air needs to be ventilated out of the house every month, otherwise water will be absorbed into the plaster of walls and timber joists etc. In addition of course the natural dampness from the ground, and building fabric needs to be extracted from the house.

Damp air condensing on a window. A similar process takes place to non-permeable materials within walls etc but is concealed from view.

Ironically the result of the ‘energy saving measures’ results in reduced ventilation that in turn can result in degradation of the building fabric. This may then require extensive timber and other repairs to be needed. These repairs including the replacement materials are likely to result in the consumption of much more energy and production of more CO2 emissions than the ‘energy saving measures’ could ever have achieved. Furthermore, the financial cost of the repair works is likely to be significantly more than any perceived energy cost saving.

When undertaking a Survey in France, I take account of the construction method adopted in the house that will influence my corresponding approach and advice as to ventilation. When undertaking RICS Surveys I also provide forward looking recommendations and care plans that will help keep the structure dry and thus naturally resilient to wood rot and insect attack, and also preserve the masonry. Accordingly the house will also be more environmentally sustainable. These principals will be valid at the date of the Survey Report and equally valid for generations to come.

When undertaking RICS Surveys in France, I see that many UK buyers tend to favour period properties either for permanent occupation or for holiday homes. When first viewing the loft space within French properties, many buyers are often concerned to see a vast array of bright spots of sunlight piercing the gaps between tiles. Furthermore, buyers may be concerned not to see felt under the tiles as is common practice in UK construction. Their immediate response is often of alarm, with concerns as to rain water cascading through the gaps, drenching everything beneath.

Often such concerns may be put to ease. It is common in France for felt not to be laid beneath the tiles, thus the underside of the tiles is exposed. The bright spots of daylight are normally via light penetrating laterally through spaces between the tiles. Clearly checks have to be made as to whether any are capable of water ingress.

No felt beneath battens allowing inspection of battens and underside of tiles.

The advantages of the traditional French approach of not using felt underlay include the following:

• The roof will benefit from improved ventilation. The air within the loft is usually warmer than the outside air, so will naturally rise up through the gaps. This draws moist air away from the house beneath, and allows ventilation to the roof joists / rafters, and battens upon which the tiles are mounted
• The underside of the tiles and battens are not obscured by felt and can be inspected to assess their condition. It also can allow for the replacement of individual broken tiles from within the loft, by carefully raising the adjoining tiles. This may be important where exterior access may be restricted by height that may require scaffold etc
• If a leak does exist, the precise location of the leak can often be seen from within the loft thus facilitating repair. If the leak were onto a felt membrane, the water would then travel over the felt, often travelling horizontally for some distance having being diverted by the horizontally fitted battens. This makes identification of the precise location of the leak difficult. The felt would also direct the water to the underside of the battens making them prone to rot.
• The absence of the felt results in a reduced weight that would otherwise be carried by the roof structure.

As a Chartered Surveyor when undertaking a detailed RICS Surveys in France I understand the logic of both traditional and modern construction. My detailed Survey Reports understand the ethos of the architecture, construction techniques and the correct approach to maintenance.  The approach to maintenance of traditional and modern buildings is necessarily very different. Armed with the French property survey report and Care Plans you can significantly reduce future maintenance and repair costs.

When buying a house in France, a Building Survey will provide a detailed assessment that is important to allow informed decisions to be made in the buying process. This also allows for evaluation of future maintenance to be built into the decision making. After all, it is not only the current condition of the property that is of importance, but also the future position. Furthermore, if the correct maintenance is adopted using the correct materials, then future maintenance costs and disruption will be significantly reduced.

Period house of traditional solid wall construction, typical in Dordogne.

Building Surveys often reveal wants of repair that ironically have been created by inappropriate maintenance. For example the use of modern ‘non-breathable’ materials on traditionally constructed buildings often results in a damp environment that promotes wood rot, insect attack and degradation. It is important that appropriate repair works are undertaken using traditional techniques and materials.

Traditional repair to a solid wall recommended within Building Survey. When buying a house in France, it is important to take account of the current condition in addition to future maintenance requirements.

In addition, there is an ever-increasing promotion of so called ‘sustainability’ or ‘green’ initiatives that seek to reduce energy consumption and CO2 emissions from houses. Whilst well intentioned, unfortunately such measures are often counterproductive when applied to traditionally constructed properties. Ironically this can result in increased degradation with associated maintenance costs and CO2 emissions in the future.

Accordingly,  appointing a Chartered Surveyor to undertake a Survey will allow you to be best placed to make informed buying decisions when buying a house in France. The Survey will analyse and detail the current condition of the property and can be tailored to also provide an understanding as to future maintenance requirements and best practice.

This is particularly important for holiday homes that may be locked and unoccupied for winter periods. In such circumstances the correct ventilation and frost protection should be maintained. This is critical for properties with traditional solid wall construction as per the illustration above. In such construction, there is no damp proof membrane within the walls and beneath the solid floors. The construction philosophy was to accept that the walls and floor will draw moisture from the ground. However, the correct level of ventilation would then allow for the evaporation and removal of the moisture. The modern approach of installing double glazed windows and reducing drafts can result in increased damp levels to then allow degradation of timber through insect attack and wood rot.

Property Surveys France undertakes Surveys in accordance with training and guidelines of its governing body, the Royal Institution of Chartered Surveyors. The RICS is the governing body of the surveying industry, headquartered in London with global reach and with the French office located in Paris.